The present disclosure herein to a semiconductor memory device and operating method thereof, and more particularly, to a flash memory device and a method program the same.
Semiconductor memory devices are memory devices implemented using semiconductor materials, such as silicon (Si), germanium (Ge), gallium arsenide (GaAs) and indium phosphide (InP). Semiconductor memory devices are largely divided into volatile memory devices and nonvolatile memory devices.
In volatile memory devices, stored data are erased when power source is shut off. Examples of volatile memory devices include Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM) and Synchronous Dynamic Random Access Memory (SDRAM). In nonvolatile memory devices, stored data is retained even when power is shut off. Examples of nonvolatile memory devices include Read-Only Memory (ROM), Programmable Read Only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), Electrical Erasable Programmable Read Only Memory (EEPROM), flash memory, Phase-change Random Access Memory (PRAM), Magnetoresistive Random Access Memory (MRAM), Resistive Random Access Memory (RRAM) and Ferroelectric Random Access Memory (FRAM). Flash memory devices are typically categorized into a NOR type and a NAND type flash memories.
Memory cells of a flash memory device have a data state that is determined according to the number of bits stored therein. A memory cell that stores 1-bit data is called a single bit cell or a Single Level Cell (SLC). A memory cell that stores multi-bit data (for example, data having two or more bits) is called a multi-bit cell or a Multi-Level Cell (MLC). With increasing demand for high integration of memory devices, research is being conducted on flash memory devices including multi-level cells.